2. New York - Norwegian Sea 



After undergoing extensive overhaul, the three ships 

 departed New York on 2 March 1962, BOWDITCH and BUTTON conducted 

 survey operations similar to those of the westbound crossing. Again, 

 their tracks corresponded roughly to great-circle routes between 

 New York and the Norwegian Sea. BUTTON maintained a position 10 miles 

 southward of BOWBITCH. MICHELSON's survey track, however, was con- 

 siderably south of the other two ships' tracks and terminated south 

 of Ireland. (Fig. 1.) 



During these crossings, severe storms made it difficult for the 

 ships to maintain their positions relative to each other. At times, 

 the ships were forced to heave to, and the magnetometer sensing units 

 were not towed. Consequently, there are several gaps in the magnetic 

 profiles obtained during these crossings. 



MICHELSON ended its survey track at 0100, 11 March, BUTTON at 

 0330, 12 March, and BOWBITCH at 1130, 13 March, after completing a 

 three-ship total of approximately 7850 miles of eastbound survey 

 tracks. Buring westbound and eastbound crossings, the three ships 

 surveyed a combined total of approximately 17,200 miles of track. 

 B. Control 



On those parts of the survey tracks lying in mid-ocean, survey 

 control was by Loran-A, with occasional celestial fixes. Navigation 

 in these areas was hampered considerably by the adverse weather con- 

 ditions. Consequently, many of the positions were determined by dead- 

 reckoning. For most of the track in midocean, the probable position 

 error is within 5 miles and is at no time considered to be greater 



